include/linux/signal.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_SIGNAL_H
   3 #define _LINUX_SIGNAL_H
   4
   5 #include <linux/bug.h>
   6 #include <linux/list.h>
   7 #include <linux/signal_types.h>
   8 #include <linux/string.h>
   9
  10 struct task_struct;
  11
  12 /* for sysctl */
  13 extern int print_fatal_signals;
  14
  15 static inline void copy_siginfo(kernel_siginfo_t *to,
  16                                 const kernel_siginfo_t *from)
  17 {
  18         memcpy(to, from, sizeof(*to));
  19 }
  20
  21 static inline void clear_siginfo(kernel_siginfo_t *info)
  22 {
  23         memset(info, 0, sizeof(*info));
  24 }
  25
  26 #define SI_EXPANSION_SIZE (sizeof(struct siginfo) - sizeof(struct kernel_siginfo))
  27
  28 static inline void copy_siginfo_to_external(siginfo_t *to,
  29                                             const kernel_siginfo_t *from)
  30 {
  31         memcpy(to, from, sizeof(*from));
  32         memset(((char *)to) + sizeof(struct kernel_siginfo), 0,
  33                 SI_EXPANSION_SIZE);
  34 }
  35
  36 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from);
  37 int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from);
  38
  39 enum siginfo_layout {
  40         SIL_KILL,
  41         SIL_TIMER,
  42         SIL_POLL,
  43         SIL_FAULT,
  44         SIL_FAULT_TRAPNO,
  45         SIL_FAULT_MCEERR,
  46         SIL_FAULT_BNDERR,
  47         SIL_FAULT_PKUERR,
  48         SIL_FAULT_PERF_EVENT,
  49         SIL_CHLD,
  50         SIL_RT,
  51         SIL_SYS,
  52 };
  53
  54 enum siginfo_layout siginfo_layout(unsigned sig, int si_code);
  55
  56 /*
  57  * Define some primitives to manipulate sigset_t.
  58  */
  59
  60 #ifndef __HAVE_ARCH_SIG_BITOPS
  61 #include <linux/bitops.h>
  62
  63 /* We don't use <linux/bitops.h> for these because there is no need to
  64    be atomic.  */
  65 static inline void sigaddset(sigset_t *set, int _sig)
  66 {
  67         unsigned long sig = _sig - 1;
  68         if (_NSIG_WORDS == 1)
  69                 set->sig[0] |= 1UL << sig;
  70         else
  71                 set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
  72 }
  73
  74 static inline void sigdelset(sigset_t *set, int _sig)
  75 {
  76         unsigned long sig = _sig - 1;
  77         if (_NSIG_WORDS == 1)
  78                 set->sig[0] &= ~(1UL << sig);
  79         else
  80                 set->sig[sig / _NSIG_BPW] &= ~(1UL << (sig % _NSIG_BPW));
  81 }
  82
  83 static inline int sigismember(sigset_t *set, int _sig)
  84 {
  85         unsigned long sig = _sig - 1;
  86         if (_NSIG_WORDS == 1)
  87                 return 1 & (set->sig[0] >> sig);
  88         else
  89                 return 1 & (set->sig[sig / _NSIG_BPW] >> (sig % _NSIG_BPW));
  90 }
  91
  92 #endif /* __HAVE_ARCH_SIG_BITOPS */
  93
  94 static inline int sigisemptyset(sigset_t *set)
  95 {
  96         switch (_NSIG_WORDS) {
  97         case 4:
  98                 return (set->sig[3] | set->sig[2] |
  99                         set->sig[1] | set->sig[0]) == 0;
 100         case 2:
 101                 return (set->sig[1] | set->sig[0]) == 0;
 102         case 1:
 103                 return set->sig[0] == 0;
 104         default:
 105                 BUILD_BUG();
 106                 return 0;
 107         }
 108 }
 109
 110 static inline int sigequalsets(const sigset_t *set1, const sigset_t *set2)
 111 {
 112         switch (_NSIG_WORDS) {
 113         case 4:
 114                 return  (set1->sig[3] == set2->sig[3]) &&
 115                         (set1->sig[2] == set2->sig[2]) &&
 116                         (set1->sig[1] == set2->sig[1]) &&
 117                         (set1->sig[0] == set2->sig[0]);
 118         case 2:
 119                 return  (set1->sig[1] == set2->sig[1]) &&
 120                         (set1->sig[0] == set2->sig[0]);
 121         case 1:
 122                 return  set1->sig[0] == set2->sig[0];
 123         }
 124         return 0;
 125 }
 126
 127 #define sigmask(sig)    (1UL << ((sig) - 1))
 128
 129 #ifndef __HAVE_ARCH_SIG_SETOPS
 130
 131 #define _SIG_SET_BINOP(name, op)                                        \
 132 static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
 133 {                                                                       \
 134         unsigned long a0, a1, a2, a3, b0, b1, b2, b3;                   \
 135                                                                         \
 136         switch (_NSIG_WORDS) {                                          \
 137         case 4:                                                         \
 138                 a3 = a->sig[3]; a2 = a->sig[2];                         \
 139                 b3 = b->sig[3]; b2 = b->sig[2];                         \
 140                 r->sig[3] = op(a3, b3);                                 \
 141                 r->sig[2] = op(a2, b2);                                 \
 142                 fallthrough;                                            \
 143         case 2:                                                         \
 144                 a1 = a->sig[1]; b1 = b->sig[1];                         \
 145                 r->sig[1] = op(a1, b1);                                 \
 146                 fallthrough;                                            \
 147         case 1:                                                         \
 148                 a0 = a->sig[0]; b0 = b->sig[0];                         \
 149                 r->sig[0] = op(a0, b0);                                 \
 150                 break;                                                  \
 151         default:                                                        \
 152                 BUILD_BUG();                                            \
 153         }                                                               \
 154 }
 155
 156 #define _sig_or(x,y)    ((x) | (y))
 157 _SIG_SET_BINOP(sigorsets, _sig_or)
 158
 159 #define _sig_and(x,y)   ((x) & (y))
 160 _SIG_SET_BINOP(sigandsets, _sig_and)
 161
 162 #define _sig_andn(x,y)  ((x) & ~(y))
 163 _SIG_SET_BINOP(sigandnsets, _sig_andn)
 164
 165 #undef _SIG_SET_BINOP
 166 #undef _sig_or
 167 #undef _sig_and
 168 #undef _sig_andn
 169
 170 #define _SIG_SET_OP(name, op)                                           \
 171 static inline void name(sigset_t *set)                                  \
 172 {                                                                       \
 173         switch (_NSIG_WORDS) {                                          \
 174         case 4: set->sig[3] = op(set->sig[3]);                          \
 175                 set->sig[2] = op(set->sig[2]);                          \
 176                 fallthrough;                                            \
 177         case 2: set->sig[1] = op(set->sig[1]);                          \
 178                 fallthrough;                                            \
 179         case 1: set->sig[0] = op(set->sig[0]);                          \
 180                     break;                                              \
 181         default:                                                        \
 182                 BUILD_BUG();                                            \
 183         }                                                               \
 184 }
 185
 186 #define _sig_not(x)     (~(x))
 187 _SIG_SET_OP(signotset, _sig_not)
 188
 189 #undef _SIG_SET_OP
 190 #undef _sig_not
 191
 192 static inline void sigemptyset(sigset_t *set)
 193 {
 194         switch (_NSIG_WORDS) {
 195         default:
 196                 memset(set, 0, sizeof(sigset_t));
 197                 break;
 198         case 2: set->sig[1] = 0;
 199                 fallthrough;
 200         case 1: set->sig[0] = 0;
 201                 break;
 202         }
 203 }
 204
 205 static inline void sigfillset(sigset_t *set)
 206 {
 207         switch (_NSIG_WORDS) {
 208         default:
 209                 memset(set, -1, sizeof(sigset_t));
 210                 break;
 211         case 2: set->sig[1] = -1;
 212                 fallthrough;
 213         case 1: set->sig[0] = -1;
 214                 break;
 215         }
 216 }
 217
 218 /* Some extensions for manipulating the low 32 signals in particular.  */
 219
 220 static inline void sigaddsetmask(sigset_t *set, unsigned long mask)
 221 {
 222         set->sig[0] |= mask;
 223 }
 224
 225 static inline void sigdelsetmask(sigset_t *set, unsigned long mask)
 226 {
 227         set->sig[0] &= ~mask;
 228 }
 229
 230 static inline int sigtestsetmask(sigset_t *set, unsigned long mask)
 231 {
 232         return (set->sig[0] & mask) != 0;
 233 }
 234
 235 static inline void siginitset(sigset_t *set, unsigned long mask)
 236 {
 237         set->sig[0] = mask;
 238         switch (_NSIG_WORDS) {
 239         default:
 240                 memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
 241                 break;
 242         case 2: set->sig[1] = 0;
 243                 break;
 244         case 1: ;
 245         }
 246 }
 247
 248 static inline void siginitsetinv(sigset_t *set, unsigned long mask)
 249 {
 250         set->sig[0] = ~mask;
 251         switch (_NSIG_WORDS) {
 252         default:
 253                 memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
 254                 break;
 255         case 2: set->sig[1] = -1;
 256                 break;
 257         case 1: ;
 258         }
 259 }
 260
 261 #endif /* __HAVE_ARCH_SIG_SETOPS */
 262
 263 static inline void init_sigpending(struct sigpending *sig)
 264 {
 265         sigemptyset(&sig->signal);
 266         INIT_LIST_HEAD(&sig->list);
 267 }
 268
 269 extern void flush_sigqueue(struct sigpending *queue);
 270
 271 /* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
 272 static inline int valid_signal(unsigned long sig)
 273 {
 274         return sig <= _NSIG ? 1 : 0;
 275 }
 276
 277 struct timespec;
 278 struct pt_regs;
 279 enum pid_type;
 280
 281 extern int next_signal(struct sigpending *pending, sigset_t *mask);
 282 extern int do_send_sig_info(int sig, struct kernel_siginfo *info,
 283                                 struct task_struct *p, enum pid_type type);
 284 extern int group_send_sig_info(int sig, struct kernel_siginfo *info,
 285                                struct task_struct *p, enum pid_type type);
 286 extern int send_signal_locked(int sig, struct kernel_siginfo *info,
 287                               struct task_struct *p, enum pid_type type);
 288 extern int sigprocmask(int, sigset_t *, sigset_t *);
 289 extern void set_current_blocked(sigset_t *);
 290 extern void __set_current_blocked(const sigset_t *);
 291 extern int show_unhandled_signals;
 292
 293 extern bool get_signal(struct ksignal *ksig);
 294 extern void signal_setup_done(int failed, struct ksignal *ksig, int stepping);
 295 extern void exit_signals(struct task_struct *tsk);
 296 extern void kernel_sigaction(int, __sighandler_t);
 297
 298 #define SIG_KTHREAD ((__force __sighandler_t)2)
 299 #define SIG_KTHREAD_KERNEL ((__force __sighandler_t)3)
 300
 301 static inline void allow_signal(int sig)
 302 {
 303         /*
 304          * Kernel threads handle their own signals. Let the signal code
 305          * know it'll be handled, so that they don't get converted to
 306          * SIGKILL or just silently dropped.
 307          */
 308         kernel_sigaction(sig, SIG_KTHREAD);
 309 }
 310
 311 static inline void allow_kernel_signal(int sig)
 312 {
 313         /*
 314          * Kernel threads handle their own signals. Let the signal code
 315          * know signals sent by the kernel will be handled, so that they
 316          * don't get silently dropped.
 317          */
 318         kernel_sigaction(sig, SIG_KTHREAD_KERNEL);
 319 }
 320
 321 static inline void disallow_signal(int sig)
 322 {
 323         kernel_sigaction(sig, SIG_IGN);
 324 }
 325
 326 extern struct kmem_cache *sighand_cachep;
 327
 328 extern bool unhandled_signal(struct task_struct *tsk, int sig);
 329
 330 /*
 331  * In POSIX a signal is sent either to a specific thread (Linux task)
 332  * or to the process as a whole (Linux thread group).  How the signal
 333  * is sent determines whether it's to one thread or the whole group,
 334  * which determines which signal mask(s) are involved in blocking it
 335  * from being delivered until later.  When the signal is delivered,
 336  * either it's caught or ignored by a user handler or it has a default
 337  * effect that applies to the whole thread group (POSIX process).
 338  *
 339  * The possible effects an unblocked signal set to SIG_DFL can have are:
 340  *   ignore     - Nothing Happens
 341  *   terminate  - kill the process, i.e. all threads in the group,
 342  *                similar to exit_group.  The group leader (only) reports
 343  *                WIFSIGNALED status to its parent.
 344  *   coredump   - write a core dump file describing all threads using
 345  *                the same mm and then kill all those threads
 346  *   stop       - stop all the threads in the group, i.e. TASK_STOPPED state
 347  *
 348  * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
 349  * Other signals when not blocked and set to SIG_DFL behaves as follows.
 350  * The job control signals also have other special effects.
 351  *
 352  *      +--------------------+------------------+
 353  *      |  POSIX signal      |  default action  |
 354  *      +--------------------+------------------+
 355  *      |  SIGHUP            |  terminate       |
 356  *      |  SIGINT            |  terminate       |
 357  *      |  SIGQUIT           |  coredump        |
 358  *      |  SIGILL            |  coredump        |
 359  *      |  SIGTRAP           |  coredump        |
 360  *      |  SIGABRT/SIGIOT    |  coredump        |
 361  *      |  SIGBUS            |  coredump        |
 362  *      |  SIGFPE            |  coredump        |
 363  *      |  SIGKILL           |  terminate(+)    |
 364  *      |  SIGUSR1           |  terminate       |
 365  *      |  SIGSEGV           |  coredump        |
 366  *      |  SIGUSR2           |  terminate       |
 367  *      |  SIGPIPE           |  terminate       |
 368  *      |  SIGALRM           |  terminate       |
 369  *      |  SIGTERM           |  terminate       |
 370  *      |  SIGCHLD           |  ignore          |
 371  *      |  SIGCONT           |  ignore(*)       |
 372  *      |  SIGSTOP           |  stop(*)(+)      |
 373  *      |  SIGTSTP           |  stop(*)         |
 374  *      |  SIGTTIN           |  stop(*)         |
 375  *      |  SIGTTOU           |  stop(*)         |
 376  *      |  SIGURG            |  ignore          |
 377  *      |  SIGXCPU           |  coredump        |
 378  *      |  SIGXFSZ           |  coredump        |
 379  *      |  SIGVTALRM         |  terminate       |
 380  *      |  SIGPROF           |  terminate       |
 381  *      |  SIGPOLL/SIGIO     |  terminate       |
 382  *      |  SIGSYS/SIGUNUSED  |  coredump        |
 383  *      |  SIGSTKFLT         |  terminate       |
 384  *      |  SIGWINCH          |  ignore          |
 385  *      |  SIGPWR            |  terminate       |
 386  *      |  SIGRTMIN-SIGRTMAX |  terminate       |
 387  *      +--------------------+------------------+
 388  *      |  non-POSIX signal  |  default action  |
 389  *      +--------------------+------------------+
 390  *      |  SIGEMT            |  coredump        |
 391  *      +--------------------+------------------+
 392  *
 393  * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
 394  * (*) Special job control effects:
 395  * When SIGCONT is sent, it resumes the process (all threads in the group)
 396  * from TASK_STOPPED state and also clears any pending/queued stop signals
 397  * (any of those marked with "stop(*)").  This happens regardless of blocking,
 398  * catching, or ignoring SIGCONT.  When any stop signal is sent, it clears
 399  * any pending/queued SIGCONT signals; this happens regardless of blocking,
 400  * catching, or ignored the stop signal, though (except for SIGSTOP) the
 401  * default action of stopping the process may happen later or never.
 402  */
 403
 404 #ifdef SIGEMT
 405 #define SIGEMT_MASK     rt_sigmask(SIGEMT)
 406 #else
 407 #define SIGEMT_MASK     0
 408 #endif
 409
 410 #if SIGRTMIN > BITS_PER_LONG
 411 #define rt_sigmask(sig) (1ULL << ((sig)-1))
 412 #else
 413 #define rt_sigmask(sig) sigmask(sig)
 414 #endif
 415
 416 #define siginmask(sig, mask) \
 417         ((sig) > 0 && (sig) < SIGRTMIN && (rt_sigmask(sig) & (mask)))
 418
 419 #define SIG_KERNEL_ONLY_MASK (\
 420         rt_sigmask(SIGKILL)   |  rt_sigmask(SIGSTOP))
 421
 422 #define SIG_KERNEL_STOP_MASK (\
 423         rt_sigmask(SIGSTOP)   |  rt_sigmask(SIGTSTP)   | \
 424         rt_sigmask(SIGTTIN)   |  rt_sigmask(SIGTTOU)   )
 425
 426 #define SIG_KERNEL_COREDUMP_MASK (\
 427         rt_sigmask(SIGQUIT)   |  rt_sigmask(SIGILL)    | \
 428         rt_sigmask(SIGTRAP)   |  rt_sigmask(SIGABRT)   | \
 429         rt_sigmask(SIGFPE)    |  rt_sigmask(SIGSEGV)   | \
 430         rt_sigmask(SIGBUS)    |  rt_sigmask(SIGSYS)    | \
 431         rt_sigmask(SIGXCPU)   |  rt_sigmask(SIGXFSZ)   | \
 432         SIGEMT_MASK                                    )
 433
 434 #define SIG_KERNEL_IGNORE_MASK (\
 435         rt_sigmask(SIGCONT)   |  rt_sigmask(SIGCHLD)   | \
 436         rt_sigmask(SIGWINCH)  |  rt_sigmask(SIGURG)    )
 437
 438 #define SIG_SPECIFIC_SICODES_MASK (\
 439         rt_sigmask(SIGILL)    |  rt_sigmask(SIGFPE)    | \
 440         rt_sigmask(SIGSEGV)   |  rt_sigmask(SIGBUS)    | \
 441         rt_sigmask(SIGTRAP)   |  rt_sigmask(SIGCHLD)   | \
 442         rt_sigmask(SIGPOLL)   |  rt_sigmask(SIGSYS)    | \
 443         SIGEMT_MASK                                    )
 444
 445 #define sig_kernel_only(sig)            siginmask(sig, SIG_KERNEL_ONLY_MASK)
 446 #define sig_kernel_coredump(sig)        siginmask(sig, SIG_KERNEL_COREDUMP_MASK)
 447 #define sig_kernel_ignore(sig)          siginmask(sig, SIG_KERNEL_IGNORE_MASK)
 448 #define sig_kernel_stop(sig)            siginmask(sig, SIG_KERNEL_STOP_MASK)
 449 #define sig_specific_sicodes(sig)       siginmask(sig, SIG_SPECIFIC_SICODES_MASK)
 450
 451 #define sig_fatal(t, signr) \
 452         (!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
 453          (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
 454
 455 void signals_init(void);
 456
 457 int restore_altstack(const stack_t __user *);
 458 int __save_altstack(stack_t __user *, unsigned long);
 459
 460 #define unsafe_save_altstack(uss, sp, label) do { \
 461         stack_t __user *__uss = uss; \
 462         struct task_struct *t = current; \
 463         unsafe_put_user((void __user *)t->sas_ss_sp, &__uss->ss_sp, label); \
 464         unsafe_put_user(t->sas_ss_flags, &__uss->ss_flags, label); \
 465         unsafe_put_user(t->sas_ss_size, &__uss->ss_size, label); \
 466 } while (0);
 467
 468 #ifdef CONFIG_DYNAMIC_SIGFRAME
 469 bool sigaltstack_size_valid(size_t ss_size);
 470 #else
 471 static inline bool sigaltstack_size_valid(size_t size) { return true; }
 472 #endif /* !CONFIG_DYNAMIC_SIGFRAME */
 473
 474 #ifdef CONFIG_PROC_FS
 475 struct seq_file;
 476 extern void render_sigset_t(struct seq_file *, const char *, sigset_t *);
 477 #endif
 478
 479 #ifndef arch_untagged_si_addr
 480 /*
 481  * Given a fault address and a signal and si_code which correspond to the
 482  * _sigfault union member, returns the address that must appear in si_addr if
 483  * the signal handler does not have SA_EXPOSE_TAGBITS enabled in sa_flags.
 484  */
 485 static inline void __user *arch_untagged_si_addr(void __user *addr,
 486                                                  unsigned long sig,
 487                                                  unsigned long si_code)
 488 {
 489         return addr;
 490 }
 491 #endif
 492
 493 #endif /* _LINUX_SIGNAL_H */